Polymerizable siloxane-quaternary amine copolymers

ABSTRACT

The present invention relates to polymeric compositions useful in the manufacture of biocompatible medical devices. More particularly, the present invention relates to certain cationic monomers capable of polymerization to form polymeric compositions having desirable physical characteristics useful in the manufacture of ophthalmic devices. Such properties include the ability to extract the polymerized medical devices with water. This avoids the use of organic solvents as is typical in the art. The polymer compositions comprise polymerized silicon-containing monomers end-capped with polymerizable cationic hydrophilic groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

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FIELD

The present invention relates to polymeric compositions useful in the manufacture of biocompatible medical devices. More particularly, the present invention relates to certain cationic monomers capable of polymerization to form polymeric compositions having desirable physical characteristics useful in the manufacture of ophthalmic devices. Such properties include the ability to extract the polymerized medical devices with water. This avoids the use of organic solvents as is typical in the art. The polymer compositions comprise polymerized silicon containing monomers end-capped with ethylenically unsaturated cationic hydrophilic groups.

BACKGROUND AND SUMMARY

Various articles, including biomedical devices, are formed of organosilicon-containing materials. One class of organosilicon materials useful for biomedical devices, such as soft contact lenses, is silicon-containing hydrogel materials. A hydrogel is a hydrated, cross linked polymeric system that contains water in an equilibrium state. Hydrogel contact lenses offer relatively high oxygen permeability as well as desirable biocompatibility and comfort. The inclusion of a silicon-containing material in the hydrogel formulation generally provides higher oxygen permeability since silicon based materials have higher oxygen permeability than water.

Another class of organosilicon materials is rigid, gas permeable materials used for hard contact lenses. Such materials are generally formed of silicon or fluorosilicon copolymers. These materials are oxygen permeable, and more rigid than the materials used for soft contact lenses. Organosilicon-containing materials useful for biomedical devices, including contact lenses, are disclosed in the following U.S. patents: U.S. Pat. No. 4,686,267 (Ellis et al.); U.S. Pat. No. 5,034,461 (Lai et al.); and U.S. Pat. No. 5,070,215 (Bambury et al.).

In addition, traditional siloxane-type monomers are hydrophobic and lenses made with them frequently require additional treatment to provide a hydrophilic surface. Although not wishing to be bound by a particular theory, the inventors believe that providing a charged siloxane-type monomer such as the quaternary siloxane-type monomers disclosed herein results in a hydrophilic siloxane-type monomer. It is believed that the hydrophilic quaternary groups interact with the electronegative portion of the polar water molecule.

Soft contact lens materials are made by polymerizing and crosslinking hydrophilic monomers such as 2-hydroxyethylmethyacrylate, N-vinyl-2-pyrrolidone, methacrylic acid and combinations thereof. The polymers produced by polymerizing these hydrophilic monomers exhibit significant hydrophilic character themselves and are capable of absorbing a significant amount of water in their polymeric matrices. Due to their ability to absorb water, these polymers are often referred to as “hydrogels”. These hydrogels are optically clear and, due to their high levels of water of hydration, are particularly useful materials for making soft contact lenses. Siloxane-type monomers are well known to be poorly soluble in water as well as hydrophilic solvents and monomers and are therefore difficult to copolymerize and process using standard hydrogel techniques. Therefore, there is a need for new siloxane-type monomers that have improved solubility in the materials, specifically the diluents, used to make hydrogel lenses. Further there is a need for monomers that result in a polymerized medical device that is extractable in water instead of the organic solvents used in the prior art.

The term “monomer” and like terms as used herein denote relatively low molecular weight compounds that are polymerizable by, for example, free radical polymerization, as well as higher molecular weight compounds also referred to as “prepolymers”, “macromonomers”, and related terms.

The term “(meth)” as used herein denotes an optional methyl substituent. Accordingly, terms such as “(meth)acrylate” denotes either methacrylate or acrylate, and “(meth)acrylic acid” denotes either methacrylic acid or acrylic acid.

The present invention provides novel cationic organosilicon-containing monomers which are useful in articles such as biomedical devices including contact lenses.

BRIEF DESCRIPTION OF THE DRAWINGS

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DETAILED DESCRIPTION

In a first aspect, the invention relates to monomers of formula (I):

wherein L can be the same or different and is selected from the group consisting of a bond, urethanes, carbonates, carbamates, carboxyl ureidos, sulfonyls, a straight or branched C1-C30 alkyl group, a C1-C30 fluoroalkyl group, a C1-C20 ester-containing group, an alkyl ether, cycloalkyl ether, cycloalkenyl ether, aryl ether, arylalkyl ether, a polyether containing group, an ureido group, an amide group, an amine group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C3-C30 cycloalkylalkyl group, a substituted or unsubstituted C3-C30 cycloalkenyl group, a substituted or unsubstituted C5-C30 aryl group, a substituted or unsubstituted C5-C30 arylalkyl group, a substituted or unsubstituted C5-C30 heteroaryl group, a substituted or unsubstituted C3-C30 heterocyclic ring, a substituted or unsubstituted C4-C30 heterocyclolalkyl group, a substituted or unsubstituted C6-C30 heteroarylalkyl group, a C5-C30 fluoroaryl group, or a hydroxyl substituted alkyl ether and combinations thereof.

X⁻ is at least a single charged counter ion. Examples of single charge counter ions include the group consisting of Cl⁻, Br⁻, I⁻, CF₃CO₂ ⁻, CH₃CO₂ ⁻, HCO₃ ⁻, CH₃SO₄ ⁻, p-toluenesulfonate, HSO₄ ⁻, H₂PO₄ ⁻, NO₃ ⁻, and CH₃CH(OH)CO₂ ⁻. Examples of dual charged counter ions would include SO₄ ²⁻, CO₃ ²⁻ and HPO₄ ²⁻. Other charged counter ions would be obvious to one of ordinary skill in the art. It should be understood that a residual amount of counter ion may be present in the hydrated product. Therefore, the use of toxic counter ions is to be discouraged. Likewise, it should be understood that, for a singularly charged counter ion, the ratio of counter ion and quaternary siloxanyl will be 1:1. Counter ions of greater negative charge will result in differing ratios based upon the total charge of the counter ion.

x and y are independently 2-200, n is an integer from 1 to about 500; R1 and R2 are each independently a straight or branched C1-C30 alkyl group, a C1-C30 fluoroalkyl group, a C1-C20 ester-containing group, an alkyl ether, cycloalkyl ether, cycloalkenyl ether, aryl ether, arylalkyl ether, a polyether containing group, an ureido group, an amide group, an amine group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C3-C30 cycloalkylalkyl group, a substituted or unsubstituted C3-C30 cycloalkenyl group, a substituted or unsubstituted C5-C30 aryl group, a substituted or unsubstituted C5-C30 arylalkyl group, a substituted or unsubstituted C5-C30 heteroaryl group, a substituted or unsubstituted C3-C30 heterocyclic ring, a substituted or unsubstituted C4-C30 heterocyclolalkyl group, a substituted or unsubstituted C6-C30 heteroarylalkyl group, fluorine, a C5-C30 fluoroaryl group, or a hydroxyl group; Z is either R1, R2 or V; and V is independently a polymerizable ethylenically unsaturated organic radical.

Representative examples of urethanes for use herein include, by way of example, a secondary amine linked to a carboxyl group which may also be linked to a further group such as an alkyl. Likewise the secondary amine may also be linked to a further group such as an alkyl.

Representative examples of carbonates for use herein include, by way of example, alkyl carbonates, aryl carbonates, and the like.

Representative examples of carbamates, for use herein include, by way of example, alkyl carbamates, aryl carbamates, and the like.

Representative examples of carboxyl ureidos, for use herein include, by way of example, alkyl carboxyl ureidos, aryl carboxyl ureidos, and the like.

Representative examples of sulfonyls for use herein include, by way of example, alkyl sulfonyls, aryl sulfonyls, and the like.

Representative examples of alkyl groups for use herein include, by way of example, a straight or branched hydrocarbon chain radical containing carbon and hydrogen atoms of from 1 to about 18 carbon atoms with or without unsaturation, to the rest of the molecule, e.g., methyl, ethyl, n-propyl, 1-methylethyl (isopropyl), n-butyl, n-pentyl, etc., and the like.

Representative examples of fluoroalkyl groups for use herein include, by way of example, a straight or branched alkyl group as defined above having one or more fluorine atoms attached to the carbon atom, e.g., —CF3, —CF2CF3, —CH2CF3, —CH2CF2H, —CF2H and the like.

Representative examples of ester-containing groups for use herein include, by way of example, a carboxylic acid ester having one to 20 carbon atoms and the like.

Representative examples of ether or polyether containing groups for use herein include, by way of example, an alkyl ether, cycloalkyl ether, cycloalkenyl ether, aryl ether, arylalkyl ether wherein the alkyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, aryl, and arylalkyl groups are defined above, e.g., alkylene oxides, poly(alkylene oxide)s such as ethylene oxide, propylene oxide, butylene oxide, poly(ethylene oxide)s, poly(ethylene glycol)s, poly(propylene oxide)s, poly(butylene oxide)s and mixtures or copolymers thereof, an ether or polyether group of the general formula —R8OR9, wherein R8 is a bond, an alkyl, cycloalkyl or aryl group as defined above and R9 is an alkyl, cycloalkyl or aryl group as defined above, e.g., —CH2CH2OC6H5 and —CH2CH2OC2H5, and the like.

Representative examples of amide groups for use herein include, by way of example, an amide of the general formula —R10C(O)NR11R12 wherein R10, R11 and R12 are independently C1-C30 hydrocarbons, e.g., R10 can be alkylene groups, arylene groups, cycloalkylene groups and R11 and R12 can be alkyl groups, aryl groups, and cycloalkyl groups as defined herein and the like.

Representative examples of amine groups for use herein include, by way of example, an amine of the general formula —R13NR14R15 wherein R13 is a C2-C30 alkylene, arylene, or cycloalkylene and R14 and R15 are independently C1-C30 hydrocarbons such as, for example, alkyl groups, aryl groups, or cycloalkyl groups as defined herein, and the like.

Representative examples of an ureido group for use herein include, by way of example, an ureido group having one or more substituents or unsubstituted ureido. The ureido group preferably is an ureido group having 1 to 12 carbon atoms. Examples of the substituents include alkyl groups and aryl groups. Examples of the ureido group include 3-methylureido, 3,3-dimethylureido, and 3-phenylureido.

Representative examples of alkoxy groups for use herein include, by way of example, an alkyl group as defined above attached via oxygen linkage to the rest of the molecule, i.e., of the general formula —OR20, wherein R20 is an alkyl, cycloalkyl, cycloalkenyl, aryl or an arylalkyl as defined above, e.g., —OCH3, —OC2H5, or —OC6H5, and the like.

Representative examples of cycloalkyl groups for use herein include, by way of example, a substituted or unsubstituted non-aromatic mono or multicyclic ring system of about 3 to about 18 carbon atoms such as, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, perhydronapththyl, adamantyl and norbornyl groups bridged cyclic group or sprirobicyclic groups, e.g., sprio-(4,4)-non-2-yl and the like, optionally containing one or more heteroatoms, e.g., O and N, and the like.

Representative examples of cycloalkylalkyl groups for use herein include, by way of example, a substituted or unsubstituted cyclic ring-containing radical containing from about 3 to about 18 carbon atoms directly attached to the alkyl group which are then attached to the main structure of the monomer at any carbon from the alkyl group that results in the creation of a stable structure such as, for example, cyclopropylmethyl, cyclobutylethyl, cyclopentylethyl and the like, wherein the cyclic ring can optionally contain one or more heteroatoms, e.g., O and N, and the like.

Representative examples of cycloalkenyl groups for use herein include, by way of example, a substituted or unsubstituted cyclic ring-containing radical containing from about 3 to about 18 carbon atoms with at least one carbon-carbon double bond such as, for example, cyclopropenyl, cyclobutenyl, cyclopentenyl and the like, wherein the cyclic ring can optionally contain one or more heteroatoms, e.g., O and N, and the like.

Representative examples of aryl groups for use herein include, by way of example, a substituted or unsubstituted monoaromatic or polyaromatic radical containing from about 5 to about 25 carbon atoms such as, for example, phenyl, naphthyl, tetrahydronapthyl, indenyl, biphenyl and the like, optionally containing one or more heteroatoms, e.g., O and N, and the like.

Representative examples of arylalkyl groups for use herein include, by way of example, a substituted or unsubstituted aryl group as defined above directly bonded to an alkyl group as defined above, e.g., —CH2C6H5, —C2H5C6H5 and the like, wherein the aryl group can optionally contain one or more heteroatoms, e.g., O and N, and the like.

Representative examples of fluoroaryl groups for use herein include, by way of example, an aryl group as defined above having one or more fluorine atoms attached to the aryl group.

Representative examples of heterocyclic ring groups for use herein include, by way of example, a substituted or unsubstituted stable 3 to about 15 membered ring radical, containing carbon atoms and from one to five heteroatoms, e.g., nitrogen, phosphorus, oxygen, sulfur and mixtures thereof. Suitable heterocyclic ring radicals for use herein may be a monocyclic, bicyclic or tricyclic ring system, which may include fused, bridged or spiro ring systems, and the nitrogen, phosphorus, carbon, oxygen or sulfur atoms in the heterocyclic ring radical may be optionally oxidized to various oxidation states. In addition, the nitrogen atom may be optionally quaternized; and the ring radical may be partially or fully saturated (i.e., heteroaromatic or heteroaryl aromatic). Examples of such heterocyclic ring radicals include, but are not limited to, azetidinyl, acridinyl, benzodioxolyl, benzodioxanyl, benzofurnyl, carbazolyl, cinnolinyl, dioxolanyl, indolizinyl, naphthyridinyl, perhydroazepinyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pyridyl, pteridinyl, purinyl, quinazolinyl, quinoxalinyl, quinolinyl, isoquinolinyl, tetrazoyl, imidazolyl, tetrahydroisouinolyl, piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, 2-oxoazepinyl, azepinyl, pyrrolyl, 4-piperidonyl, pyrrolidinyl, pyrazinyl, pyrimidinyl, pyridazinyl, oxazolyl, oxazolinyl, oxasolidinyl, triazolyl, indanyl, isoxazolyl, isoxasolidinyl, morpholinyl, thiazolyl, thiazolinyl, thiazolidinyl, isothiazolyl, quinuclidinyl, isothiazolidinyl, indolyl, isoindolyl, indolinyl, isoindolinyl, octahydroindolyl, octahydroisoindolyl, quinolyl, isoquinolyl, decahydroisoquinolyl, benzimidazolyl, thiadiazolyl, benzopyranyl, benzothiazolyl, benzooxazolyl, furyl, tetrahydrofurtyl, tetrahydropyranyl, thienyl, benzothienyl, thiamorpholinyl, thiamorpholinyl sulfoxide, thiamorpholinyl sulfone, dioxaphospholanyl, oxadiazolyl, chromanyl, isochromanyl and the like and mixtures thereof.

Representative examples of heteroaryl groups for use herein include, by way of example, a substituted or unsubstituted heterocyclic ring radical as defined above. The heteroaryl ring radical may be attached to the main structure at any heteroatom or carbon atom that results in the creation of a stable structure.

Representative examples of heteroarylalkyl groups for use herein include, by way of example, a substituted or unsubstituted heteroaryl ring radical as defined above directly bonded to an alkyl group as defined above. The heteroarylalkyl radical may be attached to the main structure at any carbon atom from the alkyl group that results in the creation of a stable structure.

Representative examples of heterocyclo groups for use herein include, by way of example, a substituted or unsubstituted heterocylic ring radical as defined above. The heterocyclo ring radical may be attached to the main structure at any heteroatom or carbon atom that results in the creation of a stable structure.

Representative examples of heterocycloalkyl groups for use herein include, by way of example, a substituted or unsubstituted heterocylic ring radical as defined above directly bonded to an alkyl group as defined above. The heterocycloalkyl radical may be attached to the main structure at carbon atom in the alkyl group that results in the creation of a stable structure.

Representative examples of a “polymerizable ethylenically unsaturated organic radicals” include, by way of example, (meth)acrylate-containing radicals, (meth)acrylamide-containing radicals, vinylcarbonate-containing radicals, vinylcarbamate-containing radicals, styrene-containing radicals and the like. In one embodiment, a polymerizable ethylenically unsaturated organic radical can be represented by the general formula:

wherein R21 is hydrogen, fluorine or methyl; R22 is independently hydrogen, fluorine, or a —CO—Y—R24 radical wherein Y is —O—, —S— or —NH— and R24 is a divalent alkylene radical having 1 to about 10 carbon atoms.

The substituents in the ‘substituted alkyl’, ‘substituted alkoxy’, ‘substituted cycloalkyl’, ‘substituted cycloalkylalkyl’, ‘substituted cycloalkenyl’, ‘substituted arylalkyl’, ‘substituted aryl’, ‘substituted heterocyclic ring’, ‘substituted heteroaryl ring,’ ‘substituted heteroarylalkyl’, ‘substituted heterocycloalkyl ring’, ‘substituted cyclic ring’ and ‘substituted carboxylic acid derivative’ may be the same or different and include one or more substituents such as hydrogen, hydroxy, halogen, carboxyl, cyano, nitro, oxo (═O), thio(═S), substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted amino, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted heterocycloalkyl ring, substituted or unsubstituted heteroarylalkyl, substituted or unsubstituted heterocyclic ring, substituted or unsubstituted guanidine, —COORx, —C(O)Rx, —C(S)Rx, —C(O)NRxRy, —C(O)ONRxRy, —NRxCONRyRz, —N(Rx)SORy, —N(Rx)SO2Ry, —(═N—N(Rx)Ry), —NRxC(O)ORy, —NRxRy, —NRxC(O)Ry—, —NRxC(S)Ry, —NRxC(S)NRyRz, —SONRxRy—, —SO2NRxRy—, —ORx, —ORxC(O)NRyRz, —ORxC(O)ORy—, —OC(O)Rx, —OC(O)NRxRy, —RxNRyC(O)Rz, —RxORy, —RxC(O)ORy, —RxC(O)NRyRz, —RxC(O)Rx, —RxOC(O)Ry, —SRx, —SORx, —SO2Rx, —ONO2, wherein Rx, Ry and Rz in each of the above groups can be the same or different and can be a hydrogen atom, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted amino, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, ‘substituted heterocycloalkyl ring’ substituted or unsubstituted heteroarylalkyl, or a substituted or unsubstituted heterocyclic ring.

Preferred monomers of Formula (I) are shown in Formula (II) through Formula (VII) below:

A schematic representation of a synthetic method for making the novel cationic silicon-containing monomers disclosed herein is provided below:

In a second aspect, the invention includes articles formed of device forming monomer mixes comprising the monomers of formula (I). According to preferred embodiments, the article is the polymerization product of a mixture comprising the aforementioned cationic monomer and at least a second monomer. Preferred articles are optically clear and useful as a contact lens.

Useful articles made with these materials may require hydrophobic, possibly silicon containing monomers. Preferred compositions have both hydrophilic and hydrophobic monomers. The invention is applicable to a wide variety of polymeric materials, either rigid or soft. Especially preferred polymeric materials are lenses including contact lenses, phakic and aphakic intraocular lenses and corneal implants although all polymeric materials including biomaterials are contemplated as being within the scope of this invention. Especially preferred are silicon containing hydrogels.

The present invention also provides medical devices such as heart valves and films, surgical devices, vessel substitutes, intrauterine devices, membranes, diaphragms, surgical implants, blood vessels, artificial ureters, artificial breast tissue and membranes intended to come into contact with body fluid outside of the body, e.g., membranes for kidney dialysis and heart/lung machines and the like, catheters, mouth guards, denture liners, ophthalmic devices, and especially contact lenses.

Silicon containing hydrogels are prepared by polymerizing a mixture containing at least one silicon-containing monomer and at least one hydrophilic monomer. The silicon-containing monomer may function as a crosslinking agent (a crosslinker being defined as a monomer having multiple polymerizable functionalities) or a separate crosslinker may be employed.

An early example of a silicon-containing contact lens material is disclosed in U.S. Pat. No. 4,153,641 (Deichert et al assigned to Bausch & Lomb Incorporated). Lenses are made from poly(organosiloxane) monomers which are α, ω terminally bonded through a divalent hydrocarbon group to a polymerized activated unsaturated group. Various hydrophobic silicon-containing prepolymers such as 1,3-bis(methacryloxyalkyl)polysiloxanes are copolymerized with known hydrophilic monomers such as 2-hydroxyethyl methacrylate (HEMA).

U.S. Pat. No. 5,358,995 (Lai et al) describes a silicon containing hydrogel which is comprised of an acrylic ester-capped polysiloxane prepolymer, polymerized with a bulky polysiloxanylalkyl(meth)acrylate monomer, and at least one hydrophilic monomer. Lai et al is assigned to Bausch & Lomb Incorporated and the entire disclosure is incorporated herein by reference. The acrylic ester-capped polysiloxane prepolymer, commonly known as M₂ D_(x) consists of two acrylic ester end groups and “x” number of repeating dimethylsiloxane units. The preferred bulky polysiloxanylalkyl(meth)acrylate monomers are TRIS-type (methacryloxypropyl tris(trimethylsiloxy)silane) with the hydrophilic monomers being either acrylic- or vinyl-containing.

Other examples of silicon-containing monomer mixtures which may be used with this invention include the following: vinyl carbonate and vinyl carbamate monomer mixtures as disclosed in U.S. Pat. Nos. 5,070,215 and 5,610,252 (Bambury et al); fluorosilicon monomer mixtures as disclosed in U.S. Pat. Nos. 5,321,108; 5,387,662 and 5,539,016 (Kunzler et al); fumarate monomer mixtures as disclosed in U.S. Pat. Nos. 5,374,662; 5,420,324 and 5,496,871 (Lai et al) and urethane monomer mixtures as disclosed in U.S. Pat. Nos. 5,451,651; 5,648,515; 5,639,908 and 5,594,085 (Lai et al), all of which are commonly assigned to assignee herein Bausch & Lomb Incorporated, and the entire disclosures of which are incorporated herein by reference.

Examples of non-silicon hydrophobic materials include alkyl acrylates and methacrylates.

The cationic silicon-containing monomers may be copolymerized with a wide variety of hydrophilic monomers to produce silicon hydrogel lenses. Suitable hydrophilic monomers include: unsaturated carboxylic acids, such as methacrylic and acrylic acids; acrylic substituted alcohols, such as 2-hydroxyethylmethacrylate and 2-hydroxyethylacrylate; vinyl lactams, such as N-vinylpyrrolidone (NVP) and 1-vinylazonan-2-one; and acrylamides, such as methacrylamide and N,N-dimethylacrylamide (DMA).

Still further examples are the hydrophilic vinyl carbonate or vinyl carbamate monomers disclosed in U.S. Pat. No. 5,070,215, and the hydrophilic oxazolone monomers disclosed in U.S. Pat. No. 4,910,277. Other suitable hydrophilic monomers will be apparent to one skilled in the art.

Hydrophobic cross linkers would include methacrylates such as ethylene glycol dimethacrylate (EGDMA) and allyl methacrylate (AMA). In contrast to traditional silicon hydrogel monomer mixtures, the monomer mixtures containing the quaternized silicon monomer of the invention herein are relatively water soluble. This feature provides advantages over traditional silicon hydrogel monomer mixtures in that there is less risk of incompatibility phase separation resulting in hazy lenses and the polymerized materials are extractable with water. However, when desired traditional organic extraction methods may also be used. In addition, the extracted lenses demonstrate a good combination of oxygen permeability (Dk) and low modulus, properties known to be important to obtaining desirable contact lenses. Moreover, lenses prepared with the quaternized silicon monomers of the invention herein are wettable even without surface treatment, provide dry mold release, do not require solvents in the monomer mix (although solvents such as glycerol may be used), the extracted polymerized material is not cytotoxic and the surface is lubricious to the touch. In cases where the polymerized monomer mix containing the quaternized silicon monomers of the invention herein do not demonstrate a desirable tear strength, toughening agents such as TBE (4-t-butyl-2-hydroxycyclohexyl methacrylate) may be added to the monomer mix. Other strengthening agents are well known to those of ordinary skill in the art and may also be used when needed.

Although an advantage of the cationic silicon-containing monomers disclosed herein is that they are relatively water soluble and also soluble in their comonomers, an organic diluent may be included in the initial monomeric mixture. As used herein, the term “organic diluent” encompasses organic compounds which minimize incompatibility of the components in the initial monomeric mixture and are substantially nonreactive with the components in the initial mixture. Additionally, the organic diluent serves to minimize phase separation of polymerized products produced by polymerization of the monomeric mixture. Also, the organic diluent will generally be relatively non-inflammable.

Contemplated organic diluents include tert-butanol (TBA); diols, such as ethylene glycol and polyols, such as glycerol. Preferably, the organic diluent is sufficiently soluble in the extraction solvent to facilitate its removal from a cured article during the extraction step. Other suitable organic diluents would be apparent to a person of ordinary skill in the art.

The organic diluent is included in an amount effective to provide the desired effect. Generally, the diluent is included at 5 to 60% by weight of the monomeric mixture, with 10 to 50% by weight being especially preferred.

According to the present process, the monomeric mixture, comprising at least one hydrophilic monomer, at least one cationic silicon-containing monomer and optionally the organic diluent, is shaped and cured by conventional methods such as static casting or spincasting.

Lens formation can be by free radical polymerization such as azobisisobutyronitrile (AIBN) and peroxide catalysts using initiators and under conditions such as those set forth in U.S. Pat. No. 3,808,179, incorporated herein by reference. Photo initiation of polymerization of the monomer mixture as is well known in the art may also be used in the process of forming an article as disclosed herein. Colorants and the like may be added prior to monomer polymerization.

Subsequently, a sufficient amount of unreacted monomer and, when present, organic diluent is removed from the cured article to improve the biocompatibility of the article. Release of non-polymerized monomers into the eye upon installation of a lens can cause irritation and other problems. Unlike other monomer mixtures that must be extracted with flammable solvents such as isopropyl alcohol, because of the properties of the novel quaternized siloxane monomers disclosed herein, non-flammable solvents including water may be used for the extraction process.

Once the biomaterials formed from the polymerized monomer mix containing the cationic silicon containing monomers disclosed herein are formed they are then extracted to prepare them for packaging and eventual use. Extraction is accomplished by exposing the polymerized materials to various solvents such as water, tert-butanol, etc. for varying periods of time. For example, one extraction process is to immerse the polymerized materials in water for about three minutes, remove the water and then immerse the polymerized materials in another aliquot of water for about three minutes, remove that aliquot of water and then autoclave the polymerized material in water or buffer solution.

Following extraction of unreacted monomers and any organic diluent, the shaped article, for example an RGP lens, is optionally machined by various processes known in the art. The machining step includes lathe cutting a lens surface, lathe cutting a lens edge, buffing a lens edge or polishing a lens edge or surface. The present process is particularly advantageous for processes wherein a lens surface is lathe cut, since machining of a lens surface is especially difficult when the surface is tacky or rubbery.

Generally, such machining processes are performed before the article is released from a mold part. After the machining operation, the lens can be released from the mold part and hydrated. Alternately, the article can be machined after removal from the mold part and then hydrated.

EXAMPLES

All solvents and reagents are obtained from Sigma-Aldrich, Milwaukee, Wis., and used as received with the exception of aminopropyl terminated poly(dimethylsiloxane), 900-1000 and 3000 g/mol, is obtained from Gelest, Inc., Morrisville, Pa., and methacryloxypropyltris(trimethylsiloxy)silane, is obtained from Silar Laboratories, Scotia, N.Y., which are both used without further purification. The monomers 2-hydroxyethyl methacrylate and 1-vinyl-2-pyrrolidone are purified using standard techniques.

Analytical Measurements

NMR: ¹H-Nuclear Magnetic Resonance (NMR) characterization is carried out using a 400 MHz Varian spectrometer using standard techniques in the art. Samples are dissolved in chloroform-d (99.8 atom % D), unless otherwise noted. Chemical shifts are determined by assigning the residual chloroform peak at 7.25 ppm. Peak areas and proton ratios are determined by integration of baseline separated peaks. Splitting patterns (s=singlet, d=doublet, t=triplet, q=quartet, m=multiplet, br=broad) and coupling constants (J/Hz) are reported when present and clearly distinguishable.

SEC: Size Exclusion Chromatography (SEC) analyses are carried out by injection of 100 μL of sample dissolved in tetrahydrofuran (THF) (5-20 mg/mL) onto a Polymer Labs PL Gel Mixed Bed E (×2) column at 35° C. using a Waters 515 HPLC pump and HPLC grade THF mobile phase flow rate of 1.0 mL/min, and detected by a Waters 410 Differential Refractometer at 35° C. Values of M_(n), M_(w), and polydispersity (PD) are determined by comparison to Polymer Lab Polystyrene narrow standards.

ESI-TOF MS: The electrospray (ESI) time of flight (TOF) MS analysis is performed on an Applied Biosystems Mariner instrument. The instrument operated in positive ion mode. The instrument is mass calibrated with a standard solution containing lysine, angiotensinogen, bradykinin (fragment 1-5) and des-Pro bradykinin. This mixture provides a seven-point calibration from 147 to 921 m/z. The applied voltage parameters are optimized from signal obtained from the same standard solution.

Stock solutions of the polymer samples are prepared as 1 mg/mL in tetrahydrofuran (THF). From these stock solutions, samples are prepared for ESI-TOF MS analysis as 30 μM solutions in isopropanol (IPA) with the addition of 2% by volume saturated NaCl in IPA. Samples are directly infused into the ESI-TOF MS instrument at a rate of 35 μL/min.

Mechanical properties and Oxygen Permeability: Modulus and elongation tests are conducted according to ASTM D-1708a, employing an Instron (Model 4502) instrument where the hydrogel film sample is immersed in borate buffered saline; an appropriate size of the film sample is gauge length 22 mm and width 4.75 mm, where the sample further has ends forming a dog bone shape to accommodate gripping of the sample with clamps of the Instron instrument, and a thickness of 200+50 microns.

Oxygen permeability (also referred to as Dk) is determined by the following procedure. Other methods and/or instruments may be used as long as the oxygen permeability values obtained therefrom are equivalent to the described method. The oxygen permeability of silicon-containing hydrogels is measured by the polarographic method (ANSI Z80.20-1998) using an O2 Permeometer Model 201T instrument (Createch, Albany, Calif. USA) having a probe containing a central, circular gold cathode at its end and a silver anode insulated from the cathode. Measurements are taken only on pre-inspected pinhole-free, flat silicon-containing hydrogel film samples of three different center thicknesses ranging from 150 to 600 microns. Center thickness measurements of the film samples may be measured using a Rehder ET-1 electronic thickness gauge. Generally, the film samples have the shape of a circular disk. Measurements are taken with the film sample and probe immersed in a bath containing circulating phosphate buffered saline (PBS) equilibrated at 35° C.+/−0.2°. Prior to immersing the probe and film sample in the PBS bath, the film sample is placed and centered on the cathode premoistened with the equilibrated PBS, ensuring no air bubbles or excess PBS exists between the cathode and the film sample, and the film sample is then secured to the probe with a mounting cap, with the cathode portion of the probe contacting only the film sample. For silicon-containing hydrogel films, it is frequently useful to employ a Teflon polymer membrane, e.g., having a circular disk shape, between the probe cathode and the film sample. In such cases, the Teflon membrane is first placed on the pre-moistened cathode, and then the film sample is placed on the Teflon membrane, ensuring no air bubbles or excess PBS exists beneath the Teflon membrane or film sample. Once measurements are collected, only data with correlation coefficient value (R2) of 0.97 or higher should be entered into the calculation of Dk value. At least two Dk measurements per thickness, and meeting R2 value, are obtained. Using known regression analyses, oxygen permeability (Dk) is calculated from the film samples having at least three different thicknesses. Any film samples hydrated with solutions other than PBS are first soaked in purified water and allowed to equilibrate for at least 24 hours, and then soaked in PHB and allowed to equilibrate for at least 12 hours. The instruments are regularly cleaned and regularly calibrated using RGP standards. Upper and lower limits are established by calculating a +/−8.8% of the Repository values established by William J. Benjamin, et al., The Oxygen Permeability of Reference Materials, Optom V is Sci 7 (12s): 95 (1997), the disclosure of which is incorporated herein in its entirety:

Material Name Repository Values Lower Limit Upper Limit Fluoroperm 30 26.2 24 29 Menicon EX 62.4 56 66 Quantum II 92.9 85 101

Abbreviations

NVP 1-Vinyl-2-pyrrolidone

TRIS Methacryloxypropyltris(trimethylsiloxy)silane

HEMA 2-Hydroxyethyl methacrylate v-64 2,2′-Azobis(2-methylpropionitrile)

PG 1,3-Propanediol

EGDMA Ethylene glycol dimethacrylate SA 2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate IMVT 1,4-bis[4-(2-methacryloxyethyl)phenylamino]anthraquinone

Unless otherwise specifically stated or made clear by its usage, all numbers used in the examples should be considered to be modified by the term “about” and to be weight percent.

Example 1 Synthesis of 4-bromobutyl Terminated poly(dimethylsiloxane)

A solution of 1,3-bis(4-bromobutyl)tetramethyldisiloxane and octamethylcyclotetrasiloxane are treated with triflic acid and allowed to react 24 h at room temperature. The reaction is then quenched with sodium bicarbonate and allowed to stir an additional 24 h. The pressure filtered product is then vacuum stripped of excess reagent until no additional reagent is collected to afford the product as clear liquid.

Example 2 Synthesis of (N,N-dimethylaminoethyl)butyl ether Terminated poly(dimethylsiloxane)

Product from example 1 dissolved in tetrahydrofuran is cannulated onto a solution of sodium N,N-dimethylaminoethoxide, solution in tetrahydrofuran at 0° C. and allowed to react one hour. The product is then dissolved in pentane, washed with water, dried over magnesium sulfate, and solvent removed under reduced pressure to afford product.

Example 3 Synthesis of Cationic Polymerizable End-Capped poly(quaternary ammonium-co-dimethylsiloxane)

A solution of N,N-Dimethylaminoethyl methacrylate, 4-bromobutyl terminated poly(dimethylsiloxane) from example 1, and (N,N-Dimethylaminoethyl)butyl ether terminated poly(dimethylsiloxane) from example 2 in ethyl acetate is heated at 60° C. for a sufficient time as monitored by GPC and/or other analytical methods to afford acceptable conversion to prepolymer.

Examples 4-11 Polymerization and Processing of Films Containing Cationic Polymerizable End-Capped poly(quaternary ammonium-co-dimethylsiloxane) Prepolymers

Liquid monomer solutions containing cationic end-capped poly(dimethylsiloxane) prepolymers from example 3 above, along with other monomers and additives common to ophthalmic materials (diluent, initiator, etc.) can be clamped between silanized glass plates at various thicknesses and polymerized using thermal decomposition of the free radical generating additive by heating 2 h at 100° C. under a nitrogen atmosphere. Contemplated formulations are listed in table 1.

TABLE 1 Example Example 3 NVP HEMA TRIS HFIPMA PG EGDMA ν-64 4 10.0 0.0 10.0 50.0 25.0 4.0 0.5 0.5 5 10.0 20.0 0.0 45.0 20.0 4.0 0.5 0.5 6 25.0 25.0 10.0 0.0 35.0 4.0 0.5 0.5 7 10.0 50.0 10.0 25.0 0.0 4.0 0.5 0.5 8 10.0 25.0 10.0 25.0 25.0 0.0 0.5 0.5 9 10.0 25.0 10.0 25.5 25.0 4.0 0.0 0.5 10 35.0 50.0 10.0 0.0 0.0 4.0 0.5 0.5 11 45.0 50.5 0.0 0.0 0.0 4.0 0.0 0.5

Example 12 Polymerization and Processing of Ophthalmic Lenses Containing Cationic Polymerizable End-Capped poly(quaternary ammonium-co-dimethylsiloxane) Prepolymer

40 uL aliquots of a soluble, liquid monomer mix containing 13.9 parts by weight of the product from example 3, 23.3 parts TRIS, 41.8 parts NVP, 13.9 parts HEMA, 5 parts PG, 0.5 parts v-64, 1.5 parts SA, and 60 ppm IMVT are sealed between poly(propylene) anterior and posterior contact lens moulds under an inert nitrogen atmosphere, transferred to an oven and heated under an inert nitrogen atmosphere 2 h at 100° C. The cooled mold pairs are separated and the dry lens released from the mold, hydrated/extracted twice in deionized H2O for a minimum of 3 min, transferred to and sealed in an autoclave vial containing a buffered saline solution and autoclaved 30 min at 121° C. 

1-20. (canceled)
 21. A silicon containing monomer end-capped with free radical polymerizable ethylenically unsaturated cationic hydrophilic groups.
 22. The silicone containing monomer of claim 21, wherein the free radical polymerizable ethylenically unsaturated cationic hydrophilic groups are terminated with a (meth)acrylate-containing moiety.
 23. The silicone containing monomer of claim 21, having one or more cationic silicone-containing units which are endcapped with the free radical polymerizable ethylenically unsaturated cationic hydrophilic groups.
 24. A monomer mixture useful for making polymerized biomaterials comprising at least one monomer of claim 21 and at least one second monomer.
 25. The monomer mixture of claim 24, further comprising in addition to the second monomer a hydrophobic monomer and a hydrophilic monomer.
 26. The monomer mixture of claim 24, wherein the second monomer is selected from the group consisting of an unsaturated carboxylic acid, acrylic substituted alcohol, vinyl lactam, acrylamide, methacrylate, hydrophilic vinyl carbonate, hydrophilic vinyl carbamate monomer, hydrophilic oxazolone monomers and mixtures thereof.
 27. The monomer mixture of claim 24, wherein the second monomer is selected from the group consisting of methacrylic acid, acrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, N-vinyl pyrrolidone, N-vinyl caprolactone, methacrylamide, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, methyl methacrylate, allyl methacrylate, 3-methacryloyloxypropyl tris(trimethylsiloxy)silane and mixtures thereof.
 28. A biomedical device comprising the silicon-containing monomer of claim 21 as a polymerized comonomer.
 29. A biomedical device comprising a polymerization product of the monomer mixture of claim
 24. 30. A biomedical device comprising a polymerization product of the monomer mixture of claim
 26. 31. The biomedical device of claim 28, wherein the device is a contact lens.
 32. The biomedical device of claim 31, wherein the contact lens is a rigid gas permeable contact lens.
 33. The biomedical device of claim 31, wherein the contact lens is a soft contact lens.
 34. The biomedical device of claim 31, wherein the contact lens is a hydrogel contact lens.
 35. The biomedical device of claim 28, wherein the device is an intraocular lens.
 36. The biomedical device of claim 35, wherein the intraocular lens is a phakic intraocular lens.
 37. The biomedical device of claim 35, wherein the intraocular lens is an aphakic intraocular lens.
 38. The biomedical device of claim 28, wherein the device is a corneal implant.
 39. The biomedical device of claim 28, wherein the device is selected from the group consisting of heart valves, intraocular lenses, films, surgical devices, vessel substitutes, intrauterine devices, membranes, diaphragms, surgical implants, blood vessels, artificial ureters, artificial breast tissue, membranes for kidney dialysis machines, membranes for heart/lung machines, catheters, mouth guards, denture liners, ophthalmic devices, and contact lenses.
 40. A method of making a biomedical device comprising: (a) providing a monomer mixture comprising the silicon-containing monomer of claim 21 and at least a second monomer; (b) subjecting the monomer mixture to free radical polymerization conditions to provide a polymerized device; and (c) extracting the polymerized device.
 41. The method of claim 40, wherein the step of extracting is performed with a non-flammable solvent.
 42. The method of claim 40 wherein the step of extracting is performed with water.
 43. The method of claim 40, further comprising the step of packaging and sterilizing the extracted polymerized device. 